Problem
Nancy has $x$ books. Braveen has triple the number of books Nancy has, plus 5 more books. Cal has double the number of books Braveen has. In total, they have 245 books. Which equation represents the total number of books for all three people? $10 x+15=245 \quad 10 x+5=245$ $7 x+10=245 \quad 6 x+5=245$
Solution
Step 1 ：Nancy has \(x\) books, Braveen has \(3x + 5\) books, and Cal has \(2(3x + 5) = 6x + 10\) books.
Step 2 ：The total number of books is \(x + (3x + 5) + (6x + 10) = 10x + 15\).
Step 3 ：\(\boxed{10x + 15 = 245}\) is the equation that represents the total number of books for all three people.
