please solve the third word problem

[barbie]

A Web music store offers two versions of a popular song. The size of the standard version is
2.7
megabytes (MB). The size of the high-quality version is
4.7
MB. Yesterday, the high-quality version was downloaded three times as often as the standard version. The total size downloaded for the two versions was
4200
MB. How many downloads of the standard version were there?

 

[math_celebrity]

A Web music store offers two versions of a popular song. The size of the standard version is
2.7
megabytes (MB). The size of the high-quality version is
4.7
MB. Yesterday, the high-quality version was downloaded three times as often as the standard version. The total size downloaded for the two versions was
4200
MB. How many downloads of the standard version were there?

Let s be the standard version downloads and h be the high quality downloads. We have two equations:

1. h = 3s
2. 2.7s + 4.7h = 4200

Substitute (1) into (2)
2.7s + 4.7(3s) = 4200
2.7s + 14.1s = 4200

Combine like terms:
16.8s = 4200

Divide each side by 16.8
s = 250