A farmhouse shelters 15 animals. Some are cows and some are ducks. Altogether there are 40 legs. Which system of equations could be used to identify how many of each type of animals are there?
PLEASE answer ASAP.

Which mathematical statements are true? 1) if 3 is an odd number, then 3 times 3 is an even number. 2) if 6 is less than 7, then 4 is greater than 7. 3) six is divisible by 3, and 10 is a multiple of 2. 4) the average of the data is greater than the largest value in the data, or it’s less than the largest value in the data. 5) the slope of a linear graph is its rate of change, and the graph’s y-intercept is the initial value. 6) if an equilateral triangle has equal angles, then all its angles will measure 45°.

How do i do this activity, is appreciated

100 points, hi, i’m not sure how to get the equation from the graph and table.