solve congruence equation with 4 parameters

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have the following equation: $(7i_2+13j_2+15)+(i_1+j_1+2)$ must be divisible by 18. The variables $ i_1, i_2$ and $j_1, j_2$ can take values 0,1,2,3,... if we pair the variables $(i_1,j_1)$ and $(i_2,j_2)$ then in a given interval, say 0-1000 (i.e. all variables accept only values in this interval), How many such solution pairs can there be?