Try this beautiful Problem based on simple Arithmetic appeared in Math Kangaroo (Kadett) 2021 Problem 17.
There are 20 questions in a quiz. Each correct answer scores 7 points, each wrong answer scores $-4$ points, and each question left blank scores 0 points. Eric took the quiz and scored 100 points. How many questions did he leave blank?
Arithmetic
Divisibility
Logic Question
Algebra by Gelfand
Math Kangaroo (Kadett), 2021
$1$
Here given that,
Total number of questions $=20$
Score of correct answer $=7$ points
Score of wrong answer $=-4$
Eric scored $=100$ points
So that mean, the score for all of the correct answers is greater than $100$.
Now we know $7\times 16 = 112$.
Now we have to count how many wrong answers are there if the score is $100$.
Remaining question $=20-(16+3)$
So, $1$ is the correct answer.
