First you have to figure out the value of x in y:
2x-5y=3
2x= 3+5y
x= 3+5y /2
the substitute the x from the first problem to the second:
3(3+5y /2) +4y= 1
(9+15y/2 + 4y = 1)multiply by 2
9+15y + 8y = 2
15y+8y= 2-9
23y = -7
y = -7/23
after you get the y, substitute it to x:
x= 3 + 5(-7/23) /2
x= 3 + -35/23 /2
x= 69/23 + -35/23 /2
x= 34/23 /2
x= 34/46