state a, b, and the y-intercept then graoh the function on a graphing calculator ONLY PROBLEMS 1, 3, 5. WILL MARK BRAINLEST PLEASE HELP MATH ISNT MY STRONG SUBJECT​

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

The students at jefferson middle school are raising money for a charity by selling t-shirts and hats. the number of t-shirts sold was 3 times the number of hats. the profit was $5 for each t-shirt sold and $2.50 for each hat sold. the students raised $840 for the charity. they used the system below to analyze their success and found the solution to be (144, 48). 5x+2.50y=840 x=3y how much did they earn from t-shirt sales?

6. sarah saved $12.75 every week for a number of weeks, w. she received an additional $25 during the last week in which she saved money. write and solve an equation to find the number of weeks, w, for which sarah had saved money if she has $114.25 now.