Question

Aflati pe a,b,c,d din egalitatile: a) (2 x a-18):5=20 ;b) (16+b x 2) x25=400 ; c) (88-70: c) x 10 =180 ; d) 3 x (99+d )-100=275

Answer 1

a) (2a - 18) : 5 = 20 /·5
2a - 18 = 100 /+18
2a = 118 /:2
a = 59.

b) (16 + 2b) · 25 = 400 /:25
16 + 2b = 16 /-16
2b = 0 /:2
b = 0.

c) (88 - 70 : c) · 10 = 180 /:10
88 - 70 : c = 18
70 : c = 88 - 18 = 70
c = 70 : 70 = 1.

d) 3 · (99 + d) - 100 = 275
297 + 3d - 100 = 275
3d + 197 = 275 /-197
3d = 78 /:3
d = 26.

/robertinni