How many solutions are there to the system of equations? 4x-5y=5 -0.8x+0.10y=0.10

4x-5y=5 -0.8x+0.10y=0.10 should be presented like this:

4x-5y=5
-0.8x+0.10y=0.10

Mult. the 2nd eqn by 100 to eliminate the fractions:

-80x + 10y = 10

Mult all terms of the first equation by 20:  80x -100y = 100

Now combine the two equations:

-80x + 10y = 10
 80x -100y = 100
           -11
          -90y = 110, or y =
                                            9

This is a first-order linear equation, so there is only one solution.  having found y = -11/9, you must now find x by subbing -11/9 for y in the first given equation.

The two equations are going to be 3x-4=y and x+y=88.
3(23)-4=65        23+65=88
Considering your problem says greater than 88, The youngest her daughter can be would be 24.
3(24)-4=68        24+68=92