Answer:
Step-by-step explanation:
Let William be x years old.
Thomas = (4 + x) years
In five years,
William = (x + 5) years
Thomas = 4 + x + 5 = (9 + x) years
Given, in five years sum of their ages is 24.
x + 5 + 9 + x = 24
2x + 14 = 24
2x = 24 - 14
2x = 10
x =

x = 5
Hence, William is 5 years old and Thomas is 9 years old.
It costs $189-(4×$20) which is $189-$80=$109
For all of these you're trying to solve for the variable. The variable is usually a number or symbol.
11) -44+n=36
Step one would be to add 44 to both sides of the equation.
N=80
12) -36=p-91
Step one would be to add -91 to both sides of the equation.
P=55
13) X-225=671
Step one you be to add 225 to both sides of the equation. Although it may seem difficult because of the big numbers, it's the same technique.
14) 19=c-(-12)
Step one on this equation will be a little different. Because there are two negative signs (-), they turn into a plus sign. Remember, two negative signs make a positive sign.
19=c+12
Now you just subtract 12 from each side of the equation.
6=C