Respuesta :

skmdshareef5454

Answer:

a=5,b=10,c=15

1)(a+b)-5(c+a)

=(5+10)-5(15+5)

=(15)-5(20)

=15-5(20)

=10(20)

=200

2)(10×15)10(5×2)

=150×10×10

=15000

3)(a-b)+(a+b)

(5-10)+(10+5)

(-5)+15

-5+15

=10

4)(2ab-45)+a

=(2×5×10-45)+5

=(100-45)+5

=55+5

=60