1.
a) 49*67+49*99+166*51
= 49*(67+99)+166*51
= 49*166+166*51
= 166*(49+51)
= 166*100
= 16600
b) 72*42+28*206-28*164
= 72*42+28*(206-164)
= 72*42+28*42
= 42*(72+28)
= 42* 100
= 4200
c) 3^3*28-3^3*18
= 3^3*(28-18)
= 3^3*10
= 270
d) 110-{130-[150-(6+2)^2+34]}
= 110-{130-[150-(6+2)^2+34]}
= 110-{130-[150-64+34]}
= 110 -{130-120}
= 110 -10 = 100
e) 5*4^2 -24 / 2^3
= (5*4^2)-(24/2^3)
= 80 - 3
= 77
2.
a) 75-5(x+3)=20
<=> 75-5x-15=20
<=> -5x = 20 -75 +15
<=> -5x = -40
<=> x = 8
b) 2x - 138 = 2^3 * 3^2
<=> 2x -138 = 8 * 9
<=> 2x - 138 = 72
<=> 2x = 210
<=> x = 105
c) 114 + (128-x ) = 254
<=> 114 +128 - x = 254
<=> -x = 254 -114 - 128
<=> -x = 12
<=> x = -12
