If the Incomes of the two companies in 1998 were equal, what was the ratio of their Expenditure?

Let the income of both companies in 1998 = Rs. $$x$$

Let expenditure of company A in 1998 = Rs. $$E_1$$

Expenditure of company B in 1998 = Rs. $$E_2$$

Profit % of company A in 1998

=> $$\frac{x - E_1}{E_1} \times 100 = 35$$

=> $$100x - 100 E_1 = 35 E_1$$

=> $$100x = 35 E_1 + 100 E_1 = 135 E_1$$

=> $$E_1 = \frac{100x}{135} = \frac{20x}{27}$$

Profit % of company B in 1998

=> $$\frac{x - E_2}{E_2} \times 100 = 30$$

=> $$100x - 100 E_2 = 30 E_2$$

=> $$100x = 30 E_2 + 100 E_2 = 130 E_2$$

=> $$E_2 = \frac{100x}{130} = \frac{10x}{13}$$

$$\therefore$$ Ratio of expenditure = $$\frac{E_1}{E_2}$$

= $$\frac{\frac{20x}{27}}{\frac{10x}{13}}$$

= $$\frac{26}{27} = 26 : 27$$