3 + 0.45*M<=8,40. Notice the equal, because you may use all the money. Then, rearranging: M<=(8.40-3)/0.45= 12, so M<=12. Now, obviously time is positive, so you may end saying 0<=M<=12, with M=0 meaning no call! :)
he would have traveled 210 miles because in half an hour he would have traveled 30 miles and in 3 hours he would have traveled 180 miles. so we have to add those up and we get our answer: 210 miles
