The answer to this equation is 16400 for sure ..
7x +16 < -5(4 - 5x)....given
7x + 16 < -20 + 25x....distributive property
16 < -20 + 18x ... subtraction property
16 + 20 < 18x.....addition property
36 < 18x
36/18 < x.....division property
2 < x
Answer:

Step-by-step explanation:
A quadratic equation in one variable given by the general expression:

Where:

The roots of this equation can be found using the quadratic formula, which is given by:

So:

As you can see, in this case:

Using the quadratic formula:

Therefore, the answer is:

In order to do these, simply translate the sentence mathematically.
1) x-15=7
2)3x+4=13
3)x+x+2+x+4=51
Hope this helped :D. Comment below if you have any questions!