Which equation has exactly ONE solution? HELP and explain if you can, thank you!

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step-by-step explanation:

answer:  

step-by-step explanation:

odd numbers are only divisible by 1 and itself.

even numbers are divisible by more than 1 and itself.

for example 6 is even because it is divisible by more than 1 and its self. 1 x 6= 6 ; 2 x 3= 6

and 7 is odd because only 7 x 1 equals seveb

(x) - (y) = (1 + 4i)

so mark-up is 0.4 multiplied by 180 = 72