This is a great exercise on translating words to math, Always begin by defining your variables. We have three unknowns here:
Let t = the number of touchdowns scored
Let f = the number of field goals scored
Let s = the number of safeties scored.
Since we know that touchdowns are worth 7 points, then 7t would be the number of points scored on all touchdowns. Likewise for the other methods of scoring. We also know that the total points scored is 30, so:
7t+3f+2s=30
The other two equations are maybe less intuitive, but just experiment to see that you have them correct,
Three times as many touchdowns as safeties. Re-phrase this as the number of touchdowns (t) is (=) three times the number of safeties (3s), so t = 3s Test this by plugging in some number for t to see if it makes the original statement correct.
Finally, the number of field goals (f) is (=) one less than the number of touchdowns (t-1), So t-1=f
Those are your three equations, which could then be solved by the usual method of elimination or substitution.
Best wishes!