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15 points pls help fast with all questions thank you-example-1
User LMH
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1 Answer

2 votes

Answer:

11a


3x\\ 4x\\ 10+2x\\ 12+2x

11b


8\\ 6\\ 7\\ 6

12

Anna is 18. Rita is 13.

13

Mark is 12.

Explanation:

Recall that the perimeter of a shape is the sum (or total) of all the edges that make up that shape. So, for the first shape, there are three Xs. We write this as
\bold{3x} so this is the perimeter.

In the second, there are four Xs, so this is
\bold{4x}.

In the third, there are two Xs and two 5s, so this is
2x+(2*5)=\bold{10+2x}.

In the fourth, there are two Xs and three 4s, so this is
2x+(3*4)=\bold{12+2x}.

If each is equal to 24, we can simply set them as equal to 24 and solve.


3x = 24\\\bold{x=8}

----


4x=24\\ \bold{x=6}

----


10+2x=24\\2x = 14\\\bold{x=7}

----


12+2x=24\\2x=12\\\bold{x=6}

If Anna is 5 years older than Rita, then
a=r+5. If their sum is 31, then
a+r=31. We can perform some substitution:


(r+5)+r=31\\5+2r=31\\2r=26\\r=13

Therefore, Rita is 13. Keep going:


a=r+5\\a=13+5\\a=18

Anna is 18.

If Dad is three times as old as Mark, then
d=3m. If the sum of their ages is 48, then
d+m=48. We can perform some algebra:


d+m=48\\m=48-d\\d=3(48-d)\\d=144-3d\\4d=144\\d=36

Dad is 36. Keep going:


d=3m\\36=3m\\m=12

Mark is 12.

Now that you've seen these, you do the bonus ;)

User Faz Ya
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