Since the 3 and 7 have 21 as a common multiple you can divide 21 by the denominator of each term and then multiply it by the numerator which get you while numbers
Let s and g represents the numbers of suits and gowns produced.
The number of zippers used is 2s+g.
The number of buttons used is 5s+8g.
In order to use all of the available zippers and buttons, we must have ...
- 2s + g = 171
- 5s + 8g = 576
Cramer's rule tells you the solution to the system
Is given by
- x = (bf-ey)/(bd-ea)
- y = (cd-fa)/(bd-ea)
Using this rule on the equations for zippers and buttons, we have
... s = (1·576 -8·171)/(1·5 -8·2) = -792/-11 = 72
... g = (171·5 -2·576)/-11 = -297/-11 = 27
72 suits and 27 gowns can be made from available zippers and buttons.
The term "autonomous" refers to an ordinary differential equation that relates the derivatives of the dependent variable as a function *only* of the dependent variable. In other words, the ODE doesn't explicitly depend on the independent variable.
Examples:

is autonomous

is *not* autonomous
He can put 4 kids in each of 9 cars and then leave the 10th car empty. Or put 2 kids in 9th car and 2 kids in 10th so all the cars would be filled
The answer is the graph b.