Question

спростить вираз:
1)-2.4а•(–5b)
2)9a-a-8b+3b
3)a+(a-10)–(15+a)
4)–4(b–4)+7(b+2)

Answer 1

please sorry i don"t know 

Answer 2

1) 12аb
2) 8a-5b
3) 2a-10a-15a-a=-24a
4) -4b+16+7b+14=3b+30=3(b+10)