Please answer both questions​

Evaluate the expression for the given value of the variable 7a - 4a for a =8

1mile equals approximately 1.6 kilometers. which best approximates the number of miles in 6 kilometers?

(05.08a)triangle abc is transformed to similar triangle a′b′c′ below: a coordinate plane is shown. triangle abc has vertices a at 2 comma 6, b at 2 comma 4, and c at 4 comma 4. triangle a prime b prime c prime has vertices a prime at 1 comma 3, b prime at 1 comma 2, and c prime at 2 comma 2. what is the scale factor of dilation? 1 over 2 1 over 3 1 over 4 1 over 5