math
posted by Paula .
Dave pays twofifth of his salary for rent, 16% of the salary for grocery and onefourth of the salary for travel. He saves the remaining $1,368. How much does he earn?
Can anybody help me?

Let x = the amount he earns.
0.4x + 0.16x + 0.25x + 1368 = x
0.81x + 1,368 = x
1,368 = x  0.81x
1,368 = 0.19x
1,368/0.19 = x
7,200 = x