Addition and Subtraction of Fractions, Free Math Quiz

$\frac{3+7}{4+4}=\frac{10}{8}=\frac{5}{4}$

$\frac{3\cdot 4+7\cdot4}{4+4}=\frac{40}{8}=5$

$\frac{3+7}{4}=\frac{10}{4}=\frac{5}{2}$

None of these.

Question 2 (1 point)

Peter and Mary, bought a pizza divided into 16 pieces.
Peter ate 5 pieces and Mary ate 4 pieces. How much of the pizza is left?

Peter and Mary, bought a pizza divided into 16 pieces.<br />
Peter ate 5 pieces and Mary ate 4 pieces. How much of the pizza is left?

$\frac{5 \cdot 9+2 \cdot 10}{2 \cdot 5}=\frac{65}{10}=\frac{13}{2}$

$\frac{9+10}{2\cdot 5}=\frac{19}{10}$

$\frac{9+10}{2+5}=\frac{19}{7}$

None of these.

$\frac{7+5-1}{3+3+3}=\frac{11}{9}$

$\frac{7\cdot 3+5\cdot 3-1\cdot 3}{3+3-3}=\frac{33}{3}=11$

$\frac{7+5-1}{3}=\frac{11}{3}$

None of these.

$\frac{3 \cdot 5+2 \cdot 5 \cdot 5+2 \cdot 3}{2+3+5}=\frac{71}{10}$

$\frac{3\cdot 5+2\cdot 5 \cdot 5+2 \cdot 3}{2\cdot 3 \cdot 5}=\frac{71}{30}$

$\frac{1+5+1}{2 \cdot 3 \cdot 5}=\frac{7}{30}$

None of these.

$LCM(6,10,15)=30\Longrightarrow \frac{(30\div 6)\cdot 5-(30\div 10)\cdot 1+(30\div 15)\cdot 2}{30}=\frac{5\cdot 5-3\cdot 1+2\cdot 2}{30}=\frac{26}{30}=\frac{13}{30}$

$LCM(6,10,15)=30\Longrightarrow \frac{5-1+2}{30}=\frac{6}{30}=\frac{1}{5}$

$LCM(6,10,15)=30\Longrightarrow \frac{\frac{5}{6}-\frac{1}{10}+\frac{2}{15}}{30}$

None of these.

Question 8 (1 point)

Bearing in mind that $LCM(8,10)=40$, how do we add the fractions $\frac{3}{10}+\frac{9}{8}=$

$\frac{3}{10} \cdot 40+\frac{9}{8} \cdot 40=3\cdot 4+9 \cdot 5=57$

$\frac{3+9}{40}=\frac{12}{40}=\frac{3}{10}$

$\frac{(40\div 10)\cdot3+(40\div 8)\cdot9}{40}=\frac{4\cdot3+5\cdot9}{40}=\frac{57}{40}$

None of these.

Question 9 (2 points)

Bearing in mind that $LCM(2,3)=6$ and $LCM(3,5)=15$, how do we solve this?
$\frac{\frac{1}{2}+\frac{5}{3}}{\frac{2}{3}+\frac{1}{5}}=$

$\frac{\frac{1}{2}+\frac{5}{3}}{\frac{2}{3}+\frac{1}{5}}=\frac{\frac{6}{5}}{\frac{3}{8}}=\frac{6\cdot 8}{5\cdot 3}=\frac{48}{15}=\frac{16}{5}$

$\frac{\frac{1}{2}+\frac{5}{3}}{\frac{2}{3}+\frac{1}{5}}=\frac{\frac{1+5}{6}}{\frac{2+1}{15}}=\frac{\frac{6}{6}}{\frac{3}{15}}=\frac{1}{\frac{1}{5}}=5$

$\frac{\frac{1}{2}+\frac{5}{3}}{\frac{2}{3}+\frac{1}{5}}=\frac{\frac{3+10}{6}}{\frac{10+3}{15}}=\frac{\frac{13}{6}}{\frac{13}{15}}=\frac{13\cdot 15}{13\cdot 6}= \frac{15}{6}=\frac{5}{2}$

None of these.

Question 10 (2 points)

Given $\frac{1}{12}+\frac{3}{25}-\frac{5}{18}$ and $LCM(12,25,18)=p$
Which of these is correct?

$\frac{1}{12}+\frac{3}{25}-\frac{5}{18}=\frac{(p\cdot 12)+(p \cdot 25)-(p \cdot 18)}{p}$

$\frac{1}{12}+\frac{3}{25}-\frac{5}{18} =\frac{(p\div 12)\cdot 1+(p\div 25)\cdot 3-(p\div 18)\cdot 5}{p}$

$\frac{1}{12}+\frac{3}{25}-\frac{5}{18}=\frac{1+3-5}{p}=-\frac{1}{9}$

None of these.

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