12. There are five unequal non-zero natural numbers, the smallest of which is 7. If one of them is reduced by 20, and the other four numbers are all increased by 5, the resulting numbers are still these five numbers. The sum of these five numbers is $\qquad$ .
【Analysis】 85
Key Point: Arithmetic Sequence; $\square$
Since 7 cannot be the number that decreases by 20, one of the five numbers must be $7+5=12$;
Similarly, one of the five numbers must also be $12+5=17$ and $17+5=22$;
If the number that decreases by 20 is 22, then one of the five numbers must be $22-20=2$, but $2<7$ does not meet the condition; therefore, one of the five numbers must also be $22+5=27$, at which point $27-20=5$ meets the condition;
That is, the five numbers are $7,12,17,22,27$, and their sum is $7+12+17+22+27=85$.