## Thinking Mathematically (6th Edition)

(a) The difference is of $128\text{ billion dollars}$ and the budget was surplus. Consider the given bar graph. From the image above, the number corresponding to given year is, Money collected for 2001 was$1991$ billion dollars. Money spent for 2001 was$1863$ billion dollars. So, the total difference in amount is, $\left( \$1991\text{billion}-\$1863\text{billion}\right)=\$128\text{billion}$Thus, the difference is of$\text{128}\,\text{billion}\,\text{dollars}$. Since it is positive, the budget is surplus. (b) The difference is of$-1413\text{ billion dollars}$and the budget was in deficit. Consider the given bar graph. From the image above, the number corresponding to given year is, Money collected in 2009 was$2105$billion dollars. Money spent in 2009 was$3518$billion dollars. So, the total difference in amount is,$\begin{align} & \text{Diff }=\text{money collected - money spent} \\ & =2105-3518 \\ & =-1413 \end{align}$Thus, the difference is of$-\text{1413}\,\,\text{billion}\,\text{dollars}$. Since it is negative, the budget is in deficit. (c) The difference is of$1541\text{ billion dollars}$. Consider the given bar graph. From the calculations in previous parts, The surplus in$2001$was$128$billion dollars. The deficit in 2009 was$-1413$billion dollars. So, the total difference in amount is,$\begin{align} & \text{Diff }=~128-\left( -1413 \right) \\ & =128+1413 \\ & =1541 \end{align}$Thus, difference is of$\text{1541}\,\,\text{billion}\,\text{dollars}\$.