apply the distance formula
\(d= \sqrt{ (x_2 - x_1)^2 +(y_2-y_1)^2}\)
except if you use the starting point of (0,0), its essentially an application of pythagorean theorem
x2 would be 15t
y2 would be -36t
and d would be 24
writing it all out would be
24^2= (15t)^2 + (-36t)^2
in which case, just expand, and solve for t
any questions?
