Hello, apologies in advance my probably stupid question but I am stuck with one calculus. Below is the calculus given in the textbook and I fail to understand how come to Y = 12 292.7 - 73.2r. Would appreciate if anyone could simplify the last steps of the calculation

Many thanks in advance

Starting with the basic GDP identity Y = C + I + G + (X – M) and substituting for each expenditure component using the equations above gives

Y = 2,000 + 0.7(Y – T) + 400 + 0.2Y – 30r + 1,500 + 1,000 – 0.1Y Substituting in the tax equation and solving for Y, we get