Question

Toby is painting his apartment. He has 4 gallons of paint. He uses 3/4 gallon for each wall. How many walls can he paint if he uses up all the paint? 5 1/2 walls5 1/3 walls 5 1/4 walls5 walls6 walls

Answer 1

We can answer this question in different ways. We can pose the problem as follows:

We posed the question as follows: with 3/4 of a gallon Toby can paint a wall, then with 4 gallons: how many can he paint?

Then, we can solve it using an operation called cross multiply as follows:

$x\cdot\frac{3}{4}\text{gallon}=4\text{gallon}\cdot1\text{wall}\Rightarrow x\cdot\frac{3}{4}=4\cdot1$

If we multiply both sides of the equation by 4/3, we have:

$x\cdot\frac{3}{4}\cdot\frac{4}{3}=4\cdot1\cdot\frac{4}{3}\Rightarrow x\cdot\frac{4}{4}\cdot\frac{3}{3}=\frac{4\cdot4}{3}\Rightarrow\frac{4}{4}=1,\frac{3}{3}=1$

Then, we have:

$x=\frac{4\cdot4}{3}\Rightarrow x=\frac{16}{3}=\frac{15}{3}+\frac{1}{3}\Rightarrow x=5+\frac{1}{3}\Rightarrow x=5\frac{1}{3}$

In summary, therefore, Toby can paint 5⅓ walls using the 4 gallons of paint he has.