Question 1196227
Let X = the number of mountain bikes the company plans to manufacture
    Y = the number of trail bikes the company plans to manufacture

Equations

(1)   60x + 40y = 1,800

(2)   70x + 50y = 2,150

Multiply equation (1) by 5/4
(3)   75x + 50y = 2,250

Subtract equation (3) by equation (2)
5x = 100
x = 100/5 
x = 20

Answer:
The company plans to manufacture 20 mountain bikes.