Question 618944
Expand then simplify by collecting like terms

First times the first number together in each of the brackets.
(in this case times 2a by 5a)= 10a^

Secondly times the first number in the first bracket by the last number in the seocnd bracket.
(times 2a by 400 = 8a

Third times the second number in the first bracket by the first in the second bracket.
(times -3 by 5a)= -15a

lastly times the last two numbers of each bracket together.
(times -3 by 4)= -12

Then collect the like terms of expanded expression 10a^ +8a-15a-12




=10a^-7a-12