Question

a) a+b =21 7a + 7 b = ?
b) a - b =34 13a - 13 b = ?
c)a + b + c=203 11a + 11 b + 11 c = ?
d ) a + b - c =38 8a + 8 b - 8 c = ?

Answer 1

$a)a+b=21 \\ 7*(a+b)=7*21 \\ 7a+7b=147 \\ b)a-b=34 \\ 13*(a-b)=13*34 \\ 13a-13b=442 \\ c)a+b+c=203 \\ 11*(a+b+c)=11*203 \\ 11a+11b+11c=2233 \\ d)a+b-c=38 \\ 8*(a+b-c)=8*38 \\ 8a+8b-8c=304$