Solving these is about doing the opposite of what's being done to the variable.
64 = 4e
In this one, you have 4 times e. To do the opposite of multiplying by 4, you need to divide by 4.
64/4 = e
16 = e
3x =102
This has 3 times x. Again, the opposite of multiplying by 3 is dividing by 3.
3x = 102
x = 102/3 = 34
t + 28 =51
Here you have 28 added to t. The opposite of adding is subtracting, so subtract 28 from both sides.
t + 28 = 51
t = 51 - 28 = 23
r - 10 = 30
Now you have 10 being subtract from r, so the opposite would be to add 10.
r - 10 = 30
r = 30 + 10 = 40
p - 11 = 39
Again, since we have "–11", we need to add 11 to both sides.
p - 11 = 39
p = 39 + 11 = 50
61 = 28 + n
If we have 28 added to n, then we need to subtract 28.
61 = 28 + n
61 - 28 = n
33 = n
95 = 5k
The opposite of multiplying by 5 is dividing by 5.
95 = 5k
95/5 = k
19 = k
So it's just seeing what's being done and doing the opposite.