3.a.(x-17) . 200 = 400
x = (400:200) +17
x = 2+ 17
x = 19
b.(x-105):21 = 15
x = (15 . 21) +105
x = 315 + 105
x = 420
c.541 + (218 - x) = 735
x = 218 -(735 - 541)
x = 218 - 194
x = 24
d.24 + 5x = $7^5$ :$7^3$
24 + 5x = $7^2$
24 + 5x = 49
5x = 49 - 24
5x= 25
e.
5 $^2x - 3$ - 2 x $5^2$=$5^2 x 3$
5^2x - 3 - 2 x 5^2 = 5^2 x 3
5^2x - 3 - 2 x 5^2 = 75
5^2x - 3 - 50 = 75
5^2x = ....
f.345