а)
1) d + 1/5 = 4/7 + 3/7
d + 1/5 = 7/7
d + 1/5 = 1
d = 1 - 1/5
d = 4/5

2) f + 4/5 = 4/7 + 3/7
f + 4/5 = 7/7
f + 4/5 = 1
f = 1 - 4/5
f = 1/5

3) b + 2/5 = 4/7 + 3/7
b + 2/5 = 7/7
b + 2/5 = 1
b = 1 - 2/5
b = 3/5

б)
1) c - 459 = 725 + 275
c = 725 + 275 + 459
c = 1459

2) x - 459 = 725 - 275
x = 725 - 275 + 459
x = 909

3) 459 - z = 725 - 275
459 - z = 450
-z = 450 - 459
z = 9

в)
1) y/5 = 2502
y = 5 250 * 2
y = 2500

2) r/100 = 2502
r = 100 250 * 2
r = 50000

3) m/5 = 250 3
m = 5 250 * 3
m = 3750