70 000 - ( 1 085 + X ) × 208 = 2 608
( 1 085 + X ) × 208 = 70 000 - 2 608
( 1 085 + X ) × 208 = 67 392
1 085 + X = 67 392 : 208
1 085 + X = 324
X = 324 - 1 085
X = - 761
Verific:
70 000 - [ 1 085 + ( - 761 ) ] × 208 = 2 608
= 70 000 - ( 1 085 - 761 ) × 208 =
= 70 000 - 324 × 208 =
= 70 000 - 67 392 =
= 2 608