Difference=subtract sum=add. just answering so you don't waste points :-)
You can read 100 pages in 5 hours.
40 pages in 2 hours. We need to get the unit rate. In this case, we need to get the number of pages read in 1 hour.
40 pages ÷ 2 hours = 20 pages per hour.
20 pages per hours * 5 hours = 100 pages.
Normally, we could add exponents.
however, that only is possible when the bases are the same
recall what exponents mean
12³=12*12*12
so we cannot add exponents for 12³*11³ because that means 12*12*12*11*11*11
it would not equal 12⁶ or 11⁶
or you could refer to the rule

notice when x=x then we can add the bases
fun fact below
we can reverse a previous exponential rule like this
since

then

therefor

we can't add the exponents because the bases are not the same
Line y=mx+b has point (0,b).
If you've got poind (0,4) - you can write, that b=4.
So this is line y=mx+4
Now slope. You've got point (1,0), so for x=1, y=0. Substitute:
m * 1 + 4 = 0
m+4 = 0
m=-4
So equation of this line is: y=-4x+4