At what point are the two equations equal

Math, Mathematics, Algebra, Formulas

Here are the basic problem parts:
1) SP - DP(1) +FF = 4Req
2) E + DP(2) = Cur

Examples:
1) If SP = 500,000, DP(1) = 0, FF = 10,750
Req = 510,750 / 4 = 127,688

2) If E = 104,250, DP(2) = 0
Cur = 104,250

At what point will DP(1&2) be the same and Cur and Req also be the same rounded to the nearest whole number

If DP is increased by the difference between Cur and Req, the values are not accurate:
127,688 - 104,250 = 23,438

1) If SP = 500,000, DP(1) = 23,438, FF = 10,750
Req = (500,000-23,438+10,750) / 4 = 121,828

2) If E = 104,250, DP(2) = 23,438
Cur = 107,688

Ideally, 18,750 should be the result.

I tried substituting Cur for Req as the should be equal to each other, but I get the following
1) SP - DP(1) +FF = 4Req
2) E + DP(2) = Cur

500,000-DP(1) +10,750 = 4 (104,250 + DP(2))
125,000-.25(DP(1)) +2,687.50 = 104,250 + DP(2)
125,000-104250+2,687.50 = .25(DP(1)) + DP(2)
18,062.50 = 1.25DP - as DP(1) and DP(2) should be the same
18,062.50 / 1.25 = DP = 14,450

Any ideas?