Question

Given the formula `x=2a(b+7)`, what is `x` if `a=3` and `b=5`?

Answer 1

`x=72`

Explanation:

Where there is an `a` substitute 3 and where there is a `b` substitute 5

`x=2a(b+7)" "->" "x=(2xx3)color(red)(xx)(5+7)`

`x=6color(red)(xx)12 = 72`

Answer 2

72

Explanation:

We can substitute the values given for a and b directly into the formula and evaluate as follows.

`x=2xx3(5+7)=6(5+7)=6xx12=72`

or distribute the bracket , then evaluate

x = 2ab + 14a

`rArrx=(2xx3xx5)+14xx3=30+42=72`