Assume the cost of one chair is x and cost of one table is y.
ATQ
2x + y = Rs. 700...(i)
x + 2y = Rs 800 ...(ii)
2xEquation(i) - Equation (ii)
4x + 2y - x - 2y = 1400 - 800
3x = 600
x = Rs 200.
y = Rs 300
mx + my =30000
m(x+y) = 30000
m = 30000/(200+300)
m = 60
Hence value of the m is 30.