The simultaneous equations are 2x - 7y = 4 (1) 3x + y = -17 (2)
Write (2) as y = - 3x - 17 (3)
Substitute (3) into (1). 2x - 7(-3x - 17) = 4 2x + 21x + 119 = 4 23x = -115 x = -5 This is the equation obtained after substituting y from the second equation into the first equation. The solution for y is y = -3(-5) - 17 = -2
300=x+1.9x I got this by dividing the problem into two parts x[the speed of the first half] plus 1.9x [the speed of the second half increased by 1.9] both of those together should give you 300. I went further and solved this...If you placed 103.5 into this problem for x you should get 300.15!
