Here, we must set up a proportion.
90/x = 45/1
Now, cross multiply.
90*1 = 45*x Multiply each
90 = 45x Our result.
Now, divide 45 by both sides to isolate the variable.
45x/45 = 90/45 Divide by both sides.
x = 90/45 Now divide
x = 2 x equals 2
Now that we know that x equals two, we also know how long it took him to drive. Add units to our answer.
Final answer: It took us 2 hours