Answer:
57
Explanation:
a = 8
b = 7
a² - b
= 8² - 7
= (8*8) - 7
= 64 - 7
= 57
You just plug in 8 as a, and 7 as b. This gives you the following equation: which becomes by squaring the 8, Then subtract 7 and you get
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which becomes 
by squaring the 8, Then subtract 7 and you get