1) -14/15 × 25/28 + $-36/37$ ÷ $-6/37$ = $-14<em>25$/$15</em>28$ + $-36$/37 ÷ $-6$/37
= -10/21 + 6
= -10/21 + 126/21
= $126-10$/21
= 116/21

2) 26/27 × $-9/65$ + $-100/101$ ÷ 50/303
= $-26<em>9$/$27</em>65$ + $-100$/101 ÷ 50/303
= -234/1755 + $-100$/101 ÷ 303/50
= -234/1755 + $-100$/101 50/303
= -234/1755 + $-5000$/30300
= -234/1755 + $-5000$/30300 3159/3159
= -234/1755 + $-15795000$/94665500
= -234/1755 + $-15795000$/94665500
= $-234<em>94665500-15795000</em>1755$/$1755\ast 94665500$ = $-2212571400-27774750000$/$33026782700$ = -30019321400/33026782700
= -150096607/1651339135

3) -30/31 × 15/124 + $-16/21$ × $-7/8$ = $-30<em>15$/$31</em>124$ + $-16$/21 7/8
= -450/3836 + $-16</em>7$/$21<em>8$ = -450/3836 + $-112$/168
= -450/3836 + $-112$/168 5743/5743
= -450/3836 + $-6424$/101472
= -450/3836 + $-6424$/101472
= $-450<em>101472-6424</em>3836$/$3836\ast 101472$ = $-45787200-24619824$/$389060352$ = -70407024/389060352
= -4400439/24253772

4) $-51/58$ ÷ $-17/25$ - 25/27 × $-81/125$ = $-51/58$ $25/-17$ - 25/27 × $-81/125$ = $51</em>25$/$58<em>17$ - 25/27 × $-81/125$ = 1275/986 - 25/27 × $-81/125$ = 1275/986 - $25</em>81$/$27<em>125$ = 1275/986 - 2025/3375
= 1275/986 - 2025/3375 1188/1188
= 1275/986 - 2397900/3981375
= 1275/986 - 2397900/3981375
= $1275<em>3981375-2397900</em>986$/$986\ast 3981375$ = $5083921875-2361724$/$3922172550$ = 5081560151/3922172550