<u><em>Question 28:</em></u>
Subtract
on both sides
Divide
on both sides
<u><em>*(Answer)*=</em></u> 
<u><em>Question 30:</em></u>
Multiply
on both sides
Subtract
on both sides
<u><em>*(Answer)*=</em></u> 
Hope This Helps
BangtanBoyScouts
Answer:
Step-by-step explanation:
4.5x=90
x=20 history
28 chemistry
42 math
They add to 90.
History test=x
Chemistry test=1.4x
Math test=(1.5)(1.4)=2.1x
They add to 90
It looks like they're multiplied, then you can simply add the exponents,
b⁸ * b⁴ = b⁸⁺⁴ = b¹²
remember, b⁸=b*b*b*b*b*b*b*b and b⁴=b*b*b*b
so b⁸ * b⁴ = b*b*b*b*b*b*b*b * b*b*b*b = b¹²