18pts: who ever gets this and solves it step by step will be called the brainliest and get 18 pts.

1. 108 as 36% of what number? write and solve a proportion to solve the problem. (step by step)

2. 72 is what percent of 480? write and solve a proportion to solve the problem. (step by step)

3. explain how mental math can be used to estimate 15% tip on a tax ride that costs $23.25

1.)

Let the number = x

Then, it would be: (x*36)/100 = 108

x*36 = 10800

x = 10800/36

x = 300

2.) Change 72 to a decimal. So it would be a .72
Then, you multiply that by 480 and your answer should be 345.6

3.) Estimate a 15% tip on a taxi ride that costs $23.25.

I will first round the cost to the nearest dollar.
$23.25 ≈ $23.00

I will now use mental math to find 10% of the cost.
$23.00 x 0.1= 2.3

5% is 1/2 of 10%, so it would be $1.15.

Finally, I will add the values to get 15% of the whatever.
2.3 x $1.15 = 3.45

The estimation of 3.45 is 3.50.

So, a 15% tip for a taxi ride for $23.25 is about $3.50.

Hope this is helpful!! :))

Sorry i meant b in the other question