Hello!
So to find the y-coordinate we need an equation for the line. The equation we can use is
y = mx + b
In this we already know m(the slope which is 3) and we can find b by plugging in the points that are given.
10 = 3(0) + b
10 = 0 + b
10 = b
So now that we've found b, we can use this in our equation
y = 4x + b
So now we can plug in the x-coordinate that we know (2) and find the y - coordinate.
y = 4(2) + 10
y = 8 + 10
y = 18
18 is your y-coordinate