Question

Solve each proportion. Where necessary, round to the nearest tenth.

4/3 = b/21
I know b=28
do I round to the nearest tenth or what?

Answer 1

28 is a whole number, so b = 28.

Your instructions say round where necessary. It's not necessary here.

Answer 2

(4/3)=(b/21) Multiply with 21
21*(4/3)=b
b=(21*4)/3
b=(84/3)
b=28

28=4*7
21=3*7
(28/21)=(4*7)/(3*7)=(4/3)