"найти значение выражения \nа) 4,6·0, 05в если а= 12 \nв=7, 8"

4,6·0,05 means multiplying 4.6 by 0.05. So, to find the value of 4,6·0,05, we substitute the values of a and b into the expression. Given that a = 12 and b = 7,8, we can write: 4,6·0,05 = 4,6 × 0,05 = 0,23

Therefore, the value of the expression 4,6·0,05 with a = 12 and b = 7,8 is 0,23.