to solve most missing number equations using addition or subtraction its usually pretty simple
1. figure out the first number. the first number is usually the goal amount. so 150
2. were do i put x? in an equation 150-63 would equal the amount she needs. so when you subtract x from 150 you'd get 63. you already know the goal number 150 goes first and the equation equals 63 so x is going to be whats subtracted from 150
3. put it all together 150(goal)-x(unknown number)=63(the amount she already had)
