The ratio of the number of boys to the number of girls in a choir is 5 to 4. There are 60 girls in the choir. How many boys are in the choir.

75

Step-by-step explanation:

for every 5 boys there are 4 girls

60 / 4 = 15

15 * 5 = 75

let's call the solutions x₁ = (5 - 2√7)/3 and x₂ = (5 + 2√7)/3

then the equation is (x-x₁)(x-x₂) = 0

if you fill that in you get a lot of numbers which you can recognize as ax²+bx+c=0.

step-by-step explanation:

you can see that a=1 (there is just an x²)

b = (-5 -2√7 + 2√7 - 5)/3 = -10/3

c = -2√7)/3 ) * (-5+2√7)/3) = -1/3

so your answer is 3x^2 – 10x – 1 = 0