(+)ing and (-)ing rational expression with like Deno?

[Kayla]

for this problem : it says simplify the rational expressions

1) 3a^ 4 / 10b^4 times 20b^2/ 9a would the answer be a^3+2 / 3 ... if not can you explain please and thankyou=)

also i need help for :
2)

m^2 +5m -24 / m-3


and
3) r^2 -3r -10 / r^2 -4