a) x+64=81=>x = 81-64=> x = 17
b) 204+x= 57 => x = 204-57=> x = 147
c) x-89=130=>x=130+89=>x=219
d) 149-x=100
x=149-100
x=49
e) 49-x=9
x=49-9
x=40
f) 7x = 490=>x = 490:7=> x = 70
g) x•32=128=>x=128:32=>x=4
h) x:15=11 => x=15•11=>x = 165
i) 225:x=9=> x = 225:9=> x = 25
j) x la puterea 7 = 11 la puterea 7 => x = 7
k) 2 la puterea x = 64
x = 6
l) 9 la puterea x = 3⁴
3⁴=81
9 la puterea x = 81
x = 2