5y- 1=3x+5…②
Solution: Obtain from ①.
y=3x-5…③
Substitute ③ into ② to get.
5(3x-5)- 1=3x+5
15x-25- 1=3x+5
15x-3x=5+25+ 1
12x=3 1
X= 3 1/ 12
Substitute x= 12/3 1 into ①.
y= 1 1/4
(2)?
2. solution: let the average speed be xkm/h and the wind speed be ykm/h.
(X+Y)*5/2= 1200
(X-Y)* 10/3= 1200
Equation 1 is transformed into X=480-Y generation equation 2 by method of substitution, and the solution is: Y=60, Y=60 generation original equation? X=420
So the average speed of the plane is 420KM/H and the wind speed is 60 km/h.