5x + 4 = 7x
Subtract 4 from both sides.
5x = 7x - 4
Subtract 7x from both sides.
5x - 7x = -4
Simplify.
-2x = -4
Divide both sides by -2.
x = 4/2
x = 2
~Hope I helped!~
X + 7x = 56 + 8
Simplifying x + 7x = 56 + 8 Combine like terms: x + 7x = 8x 8x = 56 + 8 Combine like terms: 56 + 8 = 64 8x = 64 Solving 8x = 64 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Divide each side by '8'. x = 8 Simplifying x = 8
So it seems as if the first problem is asking this:

.
If x=0.15, then 11/15*(0.15) is 0.11 or 11/100.
The second problem is asking:

To solve algebraically, you want to get rid of the denominators under the x's. To do so, you want to multiply by the Least Common Multiple (LCM) of the denominators. For 3 and 4, the LCM is 12. Multiply everything by 12 to get:
3x+6=4x+2
Now, solve for x
Subtract 4x from both sides:
-x+6=2
Subtract 6 from both sides:
-x=-4
Multiply by -1 on both sides:
x=4.