How do you work these out im confused

Multiply 520 students by 20% (0.20).

520 * 0.20 = 104

Multiply 104 students by 12.5% (0.125).

104 * 0.125 = 13

13 students were on the wrestling team.

dimes (d) = n + .80, nickels (n) = n

Make the dimes and nickels add up to $1.40 in an equation.

(n + .80) + n = 1.40

Combine like terms.

2n + .80 = 1.40

Subtract .80 from both sides.

2n = 0.60

Divide both sides by 2.

n = 0.30

Divide this by 0.05 (how many nickels are in a dollar).

0.30/0.05 = 6

d = n + 0.80 ⇒ 0.30 + 0.80 = 1.10

Divide this by 0.10 (how many dimes are in a dollar).

1.10/0.10 = 11

There are 6 nickels and 11 dimes in the bank.

the answer is b.

step-by-step explanation:

this is a direct variation proportion. y = kx

y is the total amount due, k is the constant of variation, and x is the number of texts sent.

plug in the 3.20 and the 16 to solve for the "k". this is the constant of proportionality. it is the value that will not change.

3.20 = k(16). solving you get $.20 per text.

the equation would then be y = .20x