Formula from page 3 of CAP698
Gradient/slope = change in height / distance travelled x 100 to express as %
OR
Change in ht = gradient x distance travelled/100
Substitute known values
Change in ht = 10 x 10000/100
= 1000m
Add to this the start height at the screen of 15m = 1015 m.

So the a/c will clear the 900m obstacle by 115m