Pls me with this math ! will do anything and pls show work

34 = 6x + 12.5y
3.5 = x + y

From the second equation you can find either x or y

x = 3.5 - y

Then you substitute x in the first equation with 3.5 - y

34 = 6(3.5 - y) + 12.5y
34 = 21 - 6y + 12.5y
13 = 6.5y
y = 2

So if y = 2 ...

3.5 = x + 2
x = 1.5

So she ran for 1.5 hours and biked for 2 hours