Question

the difference of two numbers is - 21 if one of them is -42 then find the other

Answer 1

let the other number be X
according to question
x-(-42)=-21
x+42= -21
x=-21-42=-63

hope it helps
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stay blessed

Answer 2

Hey mate

Given
$- 21 = - 42 - x \: or \: \\ - 21 = x - ( - 42) \\ \\ \\ so \: x = - 21 \: or \\ \: \: \: \: \: x = - 63$
Hope it helps❤