Tìm x, biết: a, 70 trừ 5 nhân x trừ 3 bằng 45; b, 10 cộng 2x băng 4 mũ 5 chia 4 mũ 3

* Hướng dẫn giải

a, $70-5(x-3)=45$

$\iff 5.\left(x-3\right)=70-45$

$\iff 5\left(x-3\right)=35$

$\iff x-3=35:5\iff x-3=7$

$\iff x=10$

b, $10+2x=4^5:4^3$

$\iff 10+2x=4^2\iff 10+2x=16$

$\iff 2x=4\iff x=2$

c, $60-3\left(x-2\right)=51$

$\iff 3\left(x-2\right)=60-51$

$\iff 3\left(x-2\right)=9$

$\iff x-2=3\iff x=5$

d, $4x-20=2^5:2^3$

$\iff 4x-20=2^2\iff 4x-20=4$

$\iff 4x=24\iff x=6$