I really hate word problems...please give me some help?

Question

An airplane leaves Los Angeles for Denver at a speed of 410 mph. Thirty minutes later, a plane going from Denver to Los Angeles leaves Denver, which is 850 miles from Los Angeles, at a speed of 460 mph. When they meet, how far are they from Denver?

Answer 1

LA------------------------Denver

　　　850miles

From LA To Denver, a plane left at a speed of 410mph at t (time) h

From Denver to LA, a plane left at a speed of 460mph at ( t - 0.5 ) h

remember this!

time = distance / speed

speed = distance / time

distance = time * speed  ( * is a multiplication mark)

t * 410 + ( t - 0.5 ) * 460 = 850

410t + 460 t - 230 = 850

870t = 1080

t= 108/87

108/87 * 410 = 44280/87 ≒ 509

850 - 509 = 341

so the answer is

341miles

　

　

Answer 2

After 30 min, the distance between plane1 and Denver is reduced to 645m. hence, 410t+460t=645 is the equation to find out the time at which they meet. t=645/870=0.741hrs. Multiply this time with speed of plane2=460 x 0.741=341miles!!!