bonjour
ex 19
a)2+11=13
b)2x4-6
=8-6
=2
c)3x(2+5)
=6+15
=21
ex 20
a)5x10-7
=50-7
=43
b)5x3-7
=15-7
=8
c)5x1-7
5-7
=-2