Răspuns:
Buna!
a) 27:a + (63:9 +8) =18
27: a+ (7+8) =18
27:a+15=18
27:a=18-15
27:a=3
a= 27:3
a=9
b) 9*b + 3*7 - 20:2=56
9*b+21-10=56
9*b+11=56
9*b = 56-11
9*b=45
b= 45:9
b=5
c) 99 - (8*2+5*3)+6*5=
=99- (16+15)+30
=99- 31 +30
=68+30
=98
d) 42+ (8-6)*8+(15-12):3
=42 +2*8 + 3:3
=42 +16+1
=58+1
=59