How would I solve this:

Question

Mr. Merrill has 3 times as many nickels as dimes. The coins have a total of $1.50. How many of each coin does he have?

Answer 1

n = 3d

5n + 10d = 150

Substitute 3d for n in second equation and solve for d. Insert that value into the first equation and solve for n. Check by inserting both values into the second equation.

Answer 2

d = number of dimes
3d = number of nickels
d + 3d = 1.50

simplify and solve the equation for d and 3d

Answer 3

ooops, I misread question. Sorry