Answer :
Set up a proportion:
5/200 = 7/x
Cross multiply:
200 * 7 = 5 * x
1400 = 5x
Divide 5 to both sides:
x = 280
5/200 = 7/x
Cross multiply:
200 * 7 = 5 * x
1400 = 5x
Divide 5 to both sides:
x = 280