(a) Taking $\overrightarrow{\mathbf{A}}=(6.00 \hat{\mathbf{i}}-8.00 \hat{\mathbf{j}})$ units, $\overrightarrow{\mathbf{B}}=(-8.00 \hat{\mathbf{i}}+3.00 \hat{\mathbf{j}})$ units, and $\overrightarrow{\mathbf{C}}=(26.0 \hat{\mathbf{i}}+19.0 \hat{\mathbf{j}})$ units, determine $a$ and $b$ such that $a \overrightarrow{\mathbf{A}}+b \overrightarrow{\mathbf{B}}+\overrightarrow{\mathbf{C}}=0$.
(b) A student has learned that a single equation cannot be solved to determine values for more than one unknown in it. How would you explain to him that both $a$ and $b$ can be determined from the single equation used in part (a)?