Question

Solve the following problems by writing an equation a) what is 80% of 9?b) 16 is what percent of 400?

Answer 1

a) 7.2 is 80% of 9

b) 16 is 4% of 400

Here, we want to solve the problems by writing an equation

a) Let x be the 80% of 9

Thus, we have it that;

`\begin{gathered} (80)/(100)*9\text{ = x} \\ \\ (720)/(100)\text{ = x} \\ \\ 100*\text{ x = 720} \\ 100x\text{ = 720} \\ \text{ x = }(720)/(100) \\ x\text{ = 7.2} \end{gathered}`

80% of 9 is 7.2

b) Let the percentage of 400 that is 16 be x

Thus, mathematically;

`\begin{gathered} (16)/(400)*100\text{ = x} \\ \\ 16*100\text{ = 400}* x \\ 1600\text{ = 400x} \\ x\text{ = }(1600)/(400) \\ x\text{ = 4\%} \end{gathered}`