1. The problem appears to involve boxes and ovals connected by plus signs with some missing numbers represented by squares (□). 2. From the given information, each line seems to illustrate a sum of numbers within these shapes and the numbers between parentheses might be sum results or intermediate sums. 3. Let's analyze problem 16: "□ + 4 \n 50 (34) 20". Here, a square plus 4 and numbers 50, 34, 20 are involved. 4. Assuming the pattern is that the sum of the numbers inside shapes matches the numbers shown, set the missing square value as $x$. 5. Then, from the given: $x + 4 = 50$ or $x + 4 = 34$ or $x + 4 = 20$. Since none obviously fits, likely the box value plus 4 equals one of those totals. 6. Considering the box and oval sums: if $x + 4 = 34$, then $x = 30$. 7. For problem 17: "48 + 3 \n □ (26) 13", similarly, assume missing square value $y$. 8. The sum here is likely $48 + 3 = 51$, but the numbers 26 and 13 suggest sum checks. 9. If the squares must satisfy $y + 3 = 26$ or $y + 3 = 13$, then $y = 23$ or $10$. Check plausibility. 10. Given the lack of clearer instructions, the problems are about finding missing values $x$ and $y$ such that given sums hold. 11. Summary answers based on best matched sums: - Problem 16: $x = 30$ - Problem 17: $y = 23$ or $10$ (choose based on context, likely 23 since 26 is in parentheses) 12. Final check: For problem 18: "63 + 7", sum is $63 + 7 = 70$. These problems appear as puzzle sums with missing values solved by simple subtraction.