(-7y)+12y-8y
=5y-8y
=-3y
5a-3分之2b+4a-3分之1b
=9a-3分之2b-3分之1b
=9a-b
(-3)×2ab+5ab×6
=-6ab+30ab
=24ab
√19p+2√19p+√19p
=4√19p