Three friends all pitch in to buy some pizza. Annie, Billy, and Chuck each gave money in the ratio of 3:5:4 respectively. If the total amount collected was $15. how much money did Billy put in?

Work Shown:

x = some positive real number, ie, x > 0

A = amount Annie chips in = 3x

B = amount Billy chips in = 5x

C = amount Chuck chips in = 4x

Amounts are in dollars.

Note the ratio A:B:C turns into 3x:5x:4x which simplifies to 3:5:4 when we divide all three parts by the GCF x.

The total amount collected was $15, meaning we can say

A+B+C = 15

3x+5x+4x = 15

12x = 15

x = 15/12

x = (3*5)/(3*4)

x = 5/4

x = 1.25

Use this x value to find the values of A, B, and C

A = 3x = 3*1.25 = 3.75

B = 5x = 5*1.25 = 6.25

C = 4x = 4*1.25 = 5

We see that Billy contributed $6.25

As a way to check, we would do the following

A+B+C = 3.75+6.25+5 = 15

So the answer is confirmed.

Also note that the ratio 3.75:6.25:5 reduces to 3:5:4 when you divide all parts by 1.25; this fact may be more obvious if you wrote the ratio in this form

3*1.25 : 5*1.25 : 4*1.25

which shows 1.25 popping up three times

26?

step-by-step explanation:

because linear equations are a lot simpler than quadratics equations, and linear equations formula is a lot easier to memorize. that's why i think they're harder.