Competition problem — Algebra — Maths Olympiad Prep

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Algebra Difficulty 1.3 Junior Find the answer

The operation $\nabla$ is defined by $a \nabla b=4 a+b$ . What is the value of $(5 \nabla 2) \nabla 2$ ?

Your answer

A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.

Solution

Using the definition, $(5 \nabla 2) \nabla 2=(4 \times 5+2) \nabla 2=22 \nabla 2=4 \times 22+2=90$ .

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