Câu 1:
a)325,2-4,95=320,25
b)3,65x4,7+3,65x4,3+3,65=3,65x(4,7+4,3+1)=3,65x10=36.5
c)1/2+1/3=3/6+2/6=5/6
d)2/13+3/11+11/13=2/13+11/13+3/11=1+11/13=24/13
Câu 2:
a) x + 15 = 40 b)720 : [ 41- (x - 5) ]= 120
x =40 - 15 [ 41 - (x-5) ]= 720÷120
x = 25 [ 41 - (x-5) ] =6
Vậy x = 25 x - 5 = 41 - 6
x - 5 = 35
x = 35 + 5
x = 40
Vậy: x = 40
Học tốt ^^
